THE REPLACING MATERIAL FOR AXIAL BUSH ON THE PLANETARY REDUCTION GEARS FOR ACTUATORS

Transcription

1 6 th INTERNATIONAL MULTIDISCIPLINARIY CONFERENCE THE REPLACING MATERIAL FOR AXIAL BUSH ON THE PLANETARY REDUCTION GEARS FOR ACTUATORS Nasui, Vasile, North University of Baia Mare, Str. Dr. Victor Babes, no. 62 / A Abstract This paper normally reflects on the research regarding the preoccupations and results of the research activities and the production experience which the authors have been working in, in the area of series production of the planetary reduction gears. This paper meets the optimization necessities of the mechanic transmissions and first of all of making products of superior performances and a technical and consumption of materials and energy. In this direction we aimed, at a great change of a hint in their construction axial bush which plays a great functional part linked to tribological aspects. Keywords: The planetary transmissions, bush sector, efficancy, fiability Notation: - P f - the consonant friction power, -L- the width of the bearing, - W- the adimensional weigh/burden, -B- the width of the bush sector, -Q- the flow necessary lubricant, - p a the allowable pressure. 1. INTRODUCTION The planetary transmissions are high technical products which have special cinematic and dynamic advantage, the best in certain area of parameter. The simple transmissions (fig. 1) which from a cinematic point of view offer the maximum of advantages, from the efficancy point of view, it represents a maximum of disadvantage. Consequently, when designing these, taking, into account the two criteria ( the cinematic and the energetic we choose compromise solutions).

2 We know many papers on the tribological aspects which affect the efficancy planetary transmissions. In general when designing planetary reduction gears we use bearing with rolling bearing, but there are after functional hints which play a part in reducing the frictions, such as the axial bush of the roll type which are found within the frontal surfaces of the dented wheels of satellite type and support of z 3 z 2 z 1 Fig.1. Planetary train gear satellite carrier. These take over the axial forces that result from the gear with bent dents working as axial bush. Their importance is great conversing the functionality and the energetic consumption as well as the weight done with the purpose of optimizing this type of axial bush in designing the planetary reduction gears is necessary due to the large series of production as well as their effects on the efficiency and the fiability. The behavior under loading of different synthesis materials proves the decrease of the portent capacity at more reduced values than the initial one in time at the mould of portent capacity and oiled classical bushes increases (fig. 2) [6] This paper is structured on 3 parts, the introduction, the 2 nd part the methodological principles of designing the axial bush and the third part the experimental research. We took into consideration the bearing on planetary reduction gears made series at SC Angred SA. Fig.2. The portent capacity [6] 4 2. THE DIMENSIONING OF THE AXIAL BEARING The dimensioning of the axial bearing at the planetary reduction gears, the construction of the axial bush planetary mechanism according to the figure 1 is shown is figure 2, to 3 satellite wheels which contains two axial bush each so, in all, on a reduction gear, there are 6 hints called rolls. These are made of an antifriction material, non ironed mixture and has a circular shape which ensures the reduction of the frictions between the mobile parts of the mechanism. The pattern of calculation regarding the dimensioning for such a type of bush taken into account contains Fig.3. Axial bearing

3 the following determining the external diameter D e because of the contract pressure) checking the heating and establishing the conditions of lubrication. We consider the following conditions with possible limited friction on a planetary transmission. The geometric elements of such a type of axial bush are represented in figure 4. The external diameter, where D e k π 4W = 2 ( 1 β ) pa, [mm], (1) Fig.4. Axial bush k is a coefficient for increasing the surface owing to the presence of the lubrication channels, k = 0,80 0,95. β- adimensional coefficient, β = D e / D i, the usual, β = 0,4..0,6. p a the allowable pressure which, in the case of the couple of material cast iron on bronze on copper is 90 dan/cm 2. Checking the heating. These are done calculating the medium temperature of the bearing by the energetic consumption or the calculation the characteristic result p m. v m and comparing it to the allowable values. The value of the diameter of the axial bush is imposed by the construction, the interior one by the axis of the satellite wheels and the exterior one should not overpass the bottom diameter of these wheels Checking the parameters of these lubrication In certain conditions of these bearing use can ensure an almost fluid lubrication by the effect of thermical distortions of thermical breakdown. We indicate the following calculation; The recommended maximum weight The dissipated power by frictions 2 2 ( D e D ) F = k [N]. (2) 1 i

4 P f = k 2 n D F [w], (3) m where: n rotation speed D- the medium diameter F- the maximum weight The necessary lubricant to limit the increase temperature over 20 0 C Q = k 3 [m 3 /s], (4) P f in which: k 1 = 0,3 ; k 2 = ; k 3 = The object of the optimization to increase the performances of bearing is to establish the couple of material and of the values of adimensional parameters D / D; L / B., of the number of sectors n s separated from the channels of lubrication and of the coefficient of designing the circular surface, defined by the expression, usual ϕ = 0,8 0,9 B n = π D s ϕ. (5) m This coefficient is useful to be taking into consideration and at this of bearing because it has a special effect on the use and the thermical balance. The planetary reduction gears functions in this direction with two types of lubricants and that is it by insertion, by sinking it or oiling under high precision where the thermic regime is overpassed. By experimental research we can find the best area of this parameter ϕ on the couple of material. 3. THE EXPERIMENTAL RESEARCH These researches have focused mainly on establishing the best material for the axial bush and of the parameters ϕ, of the way the circular surfaces function. Compared to the size and the character of the evolution of the weight as well as according to other functional conditions which reflects directly on the quality of the material of bearing, this should be closing to ensure an exploitation with maximum of fiability we especially have to take into consideration aspects such as resistance to tiredness and the propriety of antifriction, the used lubricants, the behavior at friction and the thermic regime of working, and the fabrication cost. The structure of the axial bush of roll type is presented in the following figure achieved in the existent phase by refining the non ironed composition Bz10T mould for replacement and

5 experimental research was made of synthesis material on iron symbol FU-E10-64, the same as the mixture. The proprieties of the synthesis material are the following: Composition: Cu-Sn sau Cu Al 10 Fe 3; Density 6,4-6,8 gr. /cm 3 ; Static loading < 1200 dan/ cm 2 ; Maximum linear sped 6 m /s; Allowable loading p.v = max 18; Turation of regime n< rot/min; Temperature working 20 o..+80 o C ; the oiled structure. The research consisted of endurance evidence ( of duration) on the basis of a research program which consisted of loading on the stand two sizes of bush (25 x 12 x3 ; 30 x 20 x 3,5 ) when functioning under loading. The measured parameters are represented in the table 1. Fig. 5. The pattern of the trial stand with brake for loading The measured parameters Table 1. No Measured values Obs. The name of the parameters crt. UM The medium absorbed power kw 4,9. 7,6 2 The turation of entrance rot/min The moment of braking. dan m The medium temperature, o C 46,72 o C 40 o C 5 The duration of the evidence: - when empty hour 2 2 * -when loaded. h Level of medium noise < C z 70 < C z 70 < C z 70 * Observations: An hour clockwise and an hour counterclockwise The pattern of the measurement stand is presented in figure 5. The stand is of the open a open type and contains batteries, an electric engine, the reduction gear to bi tried on aid a brake a with metallic powder. The size of the used material was determined by measuring the thickness of the bush noting small values of these after the endurance evidence, such as we have shown in the table 2, for a series of 6 pieces fixed on a reduction gear.

6 The size of the used material. Table 2. Measured values Before the evidence After the evidence ,96 3,53 3,51 3,02 2,95 3,56 3,53 3,06 3,03 3,55 3,50 3,04 3,00 3,54 3, ,01 3,55 3,50 3,03 2,98 3,52 3,49 The curves of portent capacity are presented in figure 6 4. CONCLUSIONS 62 The experimental research done on the proposed material as replacements prove their efficancy 59 under aspects that ensures a successful replacement and the introduction of a series fabrication for the whole v (m/s) productions. The experimental research on the behavior Fig. 6. Portent capacity manifesting only little decrease on the conditions of ensuring an appropriate oiling of the reduction gear (fig. 6). P (dan/cm2) P = f(v) Acknowledgement. The author have valued their own experience and the research was influenced by the production conditions at the firm where they worked SC Angred SA producer of planetary reduction gears. BIBLIOGRAPHY [1] Grafitanu, M. s.a., Organe de masini, vol. 1 si 2, Bucuresti, Editura Tehnicã, [2] Camui, C., Ionică, I., Aliaj special, înlocuitor al bronzului cu staniu. În Terotehnica şi tehnologia nr [3] Dobre, V., Alegerea materialului roţilor angrenajelor melcate funcţie de viteza. În: Construcţia de maşini nr [4] Hibbeler, R.C., Engineering Mechanics. New York, Macmillan Publishing Company Inc., [5] Năsui, V. Bazele optimizării randamentului mecanic. Editura Universităţii de Nord Baia Mare 2002 [6] Pavelescu, D. Tribologie., Editura Didactica si Pedagogica Bucuresti [7] Rãdulescu, O., Sinteze optimale în constructia de masini, Bucuresti, Editura Tehnicã, [8] Renert, M., s.a., Metodica proiectãrii constructive, Bucuresti, 1986 [9] Sonoda, K. Ishibashi,A. Power transmisission efficiency of fifferential hybrid reducers consisting of gear and traction and traction drives. In: International Gearing Conference, Mechanical Engineering Publications, London, 1994, pp [10] Teodorescu, V.N. Lagare cu alunecare. Editura Tehnica, Bucuresti Author: Dr. Vasile NASUI, Professor, North University of Baia Mare, Str.: V. Babes No 62A, Romania, E- mail: nasuiv@ubm.ro, URL: Fax